4,4,4′,4′‐Tetramethyl‐Δ<sup>2,2′</sup> ‐bipyrrolidine‐3,3′‐ dione, a Compound having the Basic Chromophore System of Indigo

Wille, Eike; Lüttke, Wolfgang

doi:10.1002/anie.197108031

Cited by 55 publications

(23 citation statements)

References 10 publications

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“…The blue color of indigo could be interpreted by Lüttke and Klessinger , also by synthesis of the “Urindigo”, the 4,4,4',4'‐tetramethyl‐2,2'‐bipyrrolidinylidine‐3,3'‐dione, a compound with the stem chromophore (OC)(NH)C=C(NH)(CO) . Its structure has been recently determined by X‐ray diffraction…”

Section: Early Work On Indigo and Its Metal Complexesmentioning

confidence: 96%

Metal Complexes of Indigo and of Some Related Ligands

Beck

Sünkel

2020

Zeitschrift anorg allge chemie

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While the first coordination compounds of indigo were reported over 100 years ago, a systematic study of the coordination chemistry of this important dye and also its structural “relatives” remained silent for over half a century. Only in the last two decades of the 20th century research on this topic started again keeps on growing ever since. It could be established, mainly by X‐ray crystallography, but also by many other modern spectroscopic techniques, that deprotonated indigo, and its deprotonated oxidized and reduced forms act as mono‐ and bidentate chelate ligands in metal complexes

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Section: Early Work On Indigo and Its Metal Complexesmentioning

confidence: 96%

Metal Complexes of Indigo and of Some Related Ligands

Beck

Sünkel

2020

Zeitschrift anorg allge chemie

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“…This shows that the substituent groups are good electron donors of these molecules, and that the increase of electron density may increase the electron transfer mobility of the molecule. [44][45]. Therefore, the results calculated by B3LYP/6-311++g(d) are discussed in detail.…”

Section: The Excited-state Hydrogen Bond Properties Of the Indigo Andmentioning

confidence: 98%

TD-DFT study on electron transfer mobility and intramolecular hydrogen bond of substituted indigo derivatives

Yang

et al. 2015

Chemical Physics Letters

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“…Semiempirical calculations performed in the 1960s to the 1980s led to the conclusion that the basic chromophore of the indigo dyes is the central C=C bond together with the adjacent C=O and N-H groups. [38][39][40][41][42][43] The excitation energies of singlet excited states of indigo have been extensively studied with ab initio methods 44,45 as well as, more recently, with time-dependent density functional theory (TDDFT) and with inclusion of solvation effects by a polarizable continuum model. [46][47][48][49] However, little attention has been paid to the photochemical reactions of indigo, such as ESIPT and trans → cis photoisomerization.…”

Section: Introductionmentioning

confidence: 99%

“…A g [(π * ) 2 ] b 2.45a Absorption spectrum of tetramethylated 2 in the gas phase 40. b See footnote b ofTable 1.…”

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confidence: 99%

Molecular mechanisms of the photostability of indigo

Yamazaki

Sobolewski

Domcke

2011

Phys. Chem. Chem. Phys.

135

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The photophysics of indigo as well as of bispyrroleindigo, the basic chromophore of indigo, has been investigated with ab initio electronic-structure calculations. Vertical electronic excitation energies and excited-state potential-energy profiles have been calculated with the CASSCF, CASPT2 and CC2 methods. The calculations reveal that indigo and bispyrroleindigo undergo intramolecular single-proton transfer between adjacent N-H and C=O groups in the (1)ππ* excited state. The nearly barrierless proton transfer provides the pathway for a very efficient deactivation of the (1)ππ* state via a conical intersection with the ground state. While a low-lying S(1)-S(0) conical intersection exists also after double-proton transfer, the latter reaction path exhibits a much higher barrier. The reaction path for trans→cis photoisomerization via the twisting of the central C=C bond has been investigated for bispyrroleindigo. It has been found that the twisting of the central C=C bond is unlikely to play a role in the photochemistry of indigo, because of a large potential-energy barrier and a rather high energy of the S(1)-S(0) conical intersection of the twisted structure. These findings indicate that the exceptional photostability of indigo is the result of rapid internal conversion via intramolecular single-proton transfer, combined with the absence of a low-barrier reaction path for the generation of the cis isomer via trans→cis photoisomerization.

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4,4,4′,4′‐Tetramethyl‐Δ^2,2′ ‐bipyrrolidine‐3,3′‐ dione, a Compound having the Basic Chromophore System of Indigo

Cited by 55 publications

References 10 publications

Metal Complexes of Indigo and of Some Related Ligands

Metal Complexes of Indigo and of Some Related Ligands

TD-DFT study on electron transfer mobility and intramolecular hydrogen bond of substituted indigo derivatives

Molecular mechanisms of the photostability of indigo

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4,4,4′,4′‐Tetramethyl‐Δ2,2′ ‐bipyrrolidine‐3,3′‐ dione, a Compound having the Basic Chromophore System of Indigo

Cited by 55 publications

References 10 publications

Metal Complexes of Indigo and of Some Related Ligands

Metal Complexes of Indigo and of Some Related Ligands

TD-DFT study on electron transfer mobility and intramolecular hydrogen bond of substituted indigo derivatives

Molecular mechanisms of the photostability of indigo

Contact Info

Product

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4,4,4′,4′‐Tetramethyl‐Δ^2,2′ ‐bipyrrolidine‐3,3′‐ dione, a Compound having the Basic Chromophore System of Indigo